尝试在空对象引用上调用虚拟方法''

• Z时代
• 2024-01-10
• 分类：问答

我收到以下错误

尝试在空对象引用上调用虚拟方法’void

android.widget.StackView.setAdapter（android.widget.Adapter）’

在这条线上

stackView.setAdapter(adapter);

完整的片段 是

public class EventsFragment extends android.support.v4.app.Fragment {
    private StackView stackView;
    private  ArrayList<Stack_Items> list;
    TypedArray eventLogo ;
    String eventName[];
    @Nullable
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        eventLogo= getResources().obtainTypedArray(R.array.event_stack_icon);
        eventName = getResources().getStringArray(R.array.event_stack);
        stackView = (StackView) getActivity().findViewById(R.id.stackView1);
        list = new ArrayList<Stack_Items>();
        //Adding items to the list
        for (int i = 0; i < eventLogo.length(); i++) {
            list.add(new Stack_Items(eventName[i], eventLogo.getResourceId(i,-1)));
        }
        //Calling adapter and setting it over stackView
        Stack_Adapter adapter = new Stack_Adapter(getActivity().getApplicationContext(), list );
        stackView.setAdapter(adapter);
        adapter.notifyDataSetChanged();
        return inflater.inflate(R.layout.events_layout, null);
    }
}

public class Stack_Adapter extends BaseAdapter {
    ArrayList<Stack_Items> arrayList;
    LayoutInflater inflater;
    ViewHolder holder = null;
    public Stack_Adapter(Context context, ArrayList<Stack_Items> arrayList) {
        this.arrayList = arrayList;
        this.inflater = LayoutInflater.from(context);
    }
    @Override
    public int getCount() {
        return arrayList.size();
    }
    @Override
    public Stack_Items getItem(int pos) {
        return arrayList.get(pos);
    }
    @Override
    public long getItemId(int pos) {
        return pos;
    }
    @Override
    public View getView(int pos, View view, ViewGroup parent) {
        if (view == null) {
            view = inflater.inflate(R.layout.stack_layout, parent, false);
            holder = new ViewHolder();
            holder.text = (TextView) view.findViewById(R.id.textView1);
            holder.image = (ImageView) view.findViewById(R.id.imageView1);
            view.setTag(holder);
        } else {
            holder = (ViewHolder) view.getTag();
        }
        holder.text.setText(arrayList.get(pos).getName());
        holder.image.setBackgroundResource(arrayList.get(pos).getImage());
        return view;
    }
    public class ViewHolder {
        TextView text;
        ImageView image;
    }
}

public class Stack_Items {
    String name;
    Integer image;
    public Stack_Items(String name, Integer image) {
        this.name = name;
        this.image = image;
    }
    public String getName() {
        return name;
    }
    public int getImage() {
        return image;
    }
}

回答：

您正在执行：

stackView = (StackView) getActivity().findViewById(R.id.stackView1);

你stackView是null。getActivity().findViewById返回null。

你为什么用getActivity()？

在哪里stackView？您应该从正确的xml加载它。

如@Tauqir所述，您需要像这样膨胀正确的xml：

View view = inflater.inflate(R.layout.events_layout, null);
stackView = (StackView) view.findViewById(R.id.stackView1);
return view;

以上是 尝试在空对象引用上调用虚拟方法'' 的全部内容， 来源链接： utcz.com/qa/411406.html